Coding Pattern with Flags for Determining Tag Data or Block Data

1. A substrate having a coding pattern disposed on a surface thereof, said coding pattern comprising a plurality of target elements defining a target grid, said target grid comprising a plurality of cells, wherein neighboring cells share target elements and a tag is defined by a plurality of contiguous cells, wherein each tag comprises: a plurality of data symbols, which comprises a plurality of first data symbols; a plurality of data elements, each of said data symbols being represented by a respective set of said data elements; and one or more flags, said one or more flags indicating either that: said first data symbols define first data contained in said tag; or said first data symbols define a fragment of second data, said second data being embedded in a block of said tags, and wherein each cell comprises: one or more translation symbols encoded by a respective set of said data elements, said translation symbols identifying a geometric translation of said cell relative to a tag containing said cell.

2. The substrate of claim 1 , wherein said first data encodes a secret-key digital signature.

3. The substrate of claim 1 , wherein said second data encodes a public-key digital signature.

4. The substrate of claim 1 , wherein said first data symbols are arranged such that any tag-sized portion of said coding pattern is guaranteed to contain said first data irrespective of whether a whole tag is contained in said portion.

5. The substrate of claim 1 , wherein said surface comprises a plurality of blocks.

6. The substrate of claim 1 , wherein said block has a width w of at least 2 tags and a height h of at least 2 tags.

7. The substrate of claim 1 , wherein said one or more flags further indicate whether said tag is contained in an active area of said surface.

8. The substrate of claim 7 , wherein said active area is selected from the group comprising: a hyperlink area, a form field area and a button area.

9. The substrate of claim 1 , wherein said coding pattern comprises: a plurality of target elements defining a target grid, said target grid comprising a plurality of cells, wherein neighboring cells share target elements and wherein each tag is defined by a plurality of contiguous cells.

10. The substrate of claim 9 , wherein each tag comprises M 2 contiguous square cells, wherein M is an integer having a value of at least 2.

11. The substrate of claim 9 , wherein a portion of data is represented by a macrodot occupying one of a plurality of possible positions within a cell, each position representing one of a plurality of possible data values.

12. The substrate of claim 9 , wherein a n-bit portion of data is represented by a macrodot occupying one of 2 n possible positions within a cell, each position representing one of 2 n possible data values, wherein n is an integer.

13. The substrate of claim 9 , wherein each cell defines a symbol group, each symbol group comprising a plurality of data symbols.

14. The substrate of claim 9 , wherein each cell comprises an orientation symbol encoded by at least one data element, said orientation symbol identifying an orientation of said coding pattern with respect to said surface.

15. The substrate of claim 1 , wherein each data symbol comprises two halves, each half comprising 2 bits of data represented by a macrodot occupying one of 4 possible positions within said half

16. The substrate of claim 1 , wherein each tag comprises a plurality of second data symbols defining at least one local codeword contained in said tag, said at least one local codeword identifying a location of a respective tag.

17. The substrate of claim 1 , wherein each tag comprises a plurality of third data symbols, said third data symbols defining one or more common codewords contained in said tag, wherein said one or more common codewords are defined as codewords common to a plurality of contiguous tags.

18. The substrate of claim 17 , wherein said third data symbols are arranged such that any tag-sized portion of said coding pattern is guaranteed to contain said one or more common codewords irrespective of whether a whole tag is contained in said portion.

19. The substrate of claim 17 , wherein said one or more common codewords encode region identity data uniquely identifying a region of said surface.